Solitary Bees
Mason Bees
Blue orchard mason bees (Osmia lignaria) are native to North America. There is also the horned-face mason bee (Osmia cornifrons) which was intentionally introduced from Asia to the United States to increase pollination of fruit crops. Both are excellent spring pollinators.
Mason bees belly flop from flower to flower, spreading pollen along the way. Compare this to the fastidious honey bee, who neatly packs pollen into the corbiculae on her hind legs. Honey bees are so efficient at collecting pollen, that they really only drop or exchange pollen on a tiny fraction of the flowers they visit, compared to mason bees which pollinate 99% of the flowers they land on.
Mason bees make nests in reeds or tubular holes and separate the brood within a nest by mud dividers. Within each chamber between the mud dividers, each mason bee larva will eventually spin its own tough little waterproof cocoon.
Mason bees are solitary but gregarious. Each bee nests in its own tube, but they don’t mind if their tube is in a house or condo next to other mason bee tubes. They also don’t mind if you stand and watch their comings and goings!
Don’t mistake mason bees with carpenter bees. Mason bees can’t drill holes in wood. They make their homes in existing cavities.
Leafcutter Bees
Alfalfa leafcutter bees (Megachile rotundata) are similar to mason bees with a few key differences. They are excellent summer pollinators, belly-flopping from flower to flower.
Leafcutter bees also make nests in reeds or tubular holes, but the females build little leafy cocoons for their offspring instead of using mud. Cocoons are delicate and look like little rolled cigars.
Preferred leaves are smooth but sturdy (rose, lilac, hosta, dahlia, peas, beans, strawberries, etc). You may see some circular holes on the edges of leaves. Though their leafcutting may sound like a nuisance, they are only collecting enough to make their cocoons. They aren’t eating the leaves and are typically not causing any sort of long-term damage to the plant. Leafcutter bees also can’t drill holes in wood. They make their homes in existing cavities.
Llike mason bees, leafcutter bees are solitary but gregarious. Each bee nests in its own tube, but they don’t mind if their tube is in a house or condo next to other leafcutter bee tubes. You can watch leafcutter bees come and go as they collect food and leafy snippets, though they can be shy.
You can keep both and pollinate throughout the growing season!
Mason Bees
-
Active in the spring (>55°F).
Good for nut tree, fruit tree, and berry bush pollination. - Prefer larger nesting holes, about 8mm in diameter.
-
Only travel about 300ft (100m) from the nest.
Need flowers and clayey mud nearby. - Overwinter as adults in tough, waterproof cocoons.
- Males are smaller with longer antennae and a white tuft of hair on their head. They emerge earlier than females.
- Females have larger bodies, shorter antennae, and large jaws.
Leafcutter Bees
-
Active in the summer (>75°F).
Good for tomato, pepper, and squash pollination. - Prefer smaller nesting holes, about 6mm in diameter.
-
Only travel about 300ft (100m) from the nest.
Need flowers and thin, sturdy leaves nearby. - Overwinter as larvae in cocoons made of leaves (NOT waterproof).
- Males are smaller with longer antennae, large tufts of hair, and bright green eyes. They emerge earlier than females.
- Females have larger bodies, white belly hair, and large jaws.
